1. Field of the Invention
This invention relates to washing additives which can be added to wash liquors to increase their detergent effect. The addition of the additives of the invention improves the removal of bleachable stains and of fat-, oil- and pigment-containing soil from fabrics to be washed.
2. Description of Related Art
In the washing of fabrics, the wash liquor is generally heated to a temperature considerably beyond room temperature. This measure increases the detergent effect of the detergents used; in some cases, to a considerable extent. However, the heating of the wash liquor and of the fabrics involves increased energy consumption during washing. Since, in addition, certain fabrics, particularly fabrics of wool or synthetic fibers, cannot be washed at elevated temperatures for various reasons, attempts have repeatedly been made to obtain good washing results at low temperatures. At low washing temperatures, however, the effect of the per compounds, frequently used for removing bleachable stains, is reduced; in some cases considerably, or even weakened to such an extent that stains cannot be removed. For this reason, so-called bleach activators are added to detergents to increase their bleaching effect, intensifying the bleaching effect of the per compounds and allowing them to be developed even at low washing temperatures. However, the simultaneous presence of per compounds and bleach activators in detergents reduces their stability in storage, particularly if the materials cannot be protected against moisture during storage. Attempts to improve stability generally resulted in a considerable reduction in the bleaching effect of the detergents. Because of this, it has already been proposed to store the bleach activator separately from the detergent containing the per compound and to add at least part of the activator to the wash liquor just before it is used. With a view to solving this problem, German Application No. 27 44 642 proposes a detergent additive which contains an organic bleach activator in water-releasable combination with a non-particulate substrate. In addition to the bleach activator and optional release aids, the detergent additive according to German Application No. 27 44 642 may contain further additives such as, for example, foam modifiers, chelating agents, soil suspending agents, optical brighteners, bactericides, anti-clouding agents, enzymes, fabric softeners and fragrances. By separating the bleach activator and the bleaching per compound from one another until just before use, it is possible to avoid the problems that arise when per compounds and bleach activators are stored together. A further improvement in the detergency of detergents based on anionic surfactants and inorganic per salts can be obtained by using the additive of German Application No. 28 57 153, which, in addition to a bleach activator, contain on a substrate a combination of an alkoxylated nonionic surfactant and a cationic surfactant containing a C.sub.8 -C.sub.20 -radical and, for the rest, C.sub.1 -C.sub.4 -radicals. However, one disadvantage of this known additive lies in the fact that, on removing the additive from its pack and adding it to the wash liquor, the user comes into contact with the active constituents which, apart from--in some cases--an unpleasant feeling, can cause skin irritation. Another disadvantage of this known additive is that, after washing, the water-insoluble substrate has to be disentangled from the washed fabrics.